Context

Thames Water's Wheatley municipal sewage wastewater treatment plant is located approximately 6 miles east of Oxford. Wheatley’s proximity to Oxford (and all points south) makes it a very attractive location for commuters, and as the housing stock and population in Wheatley and the neighbouring areas has grown, so too has the demand for essential services.

Challenge

The existing Wheatley plant had a number of immediate problems, including:

  • Insufficient capacity to deal with increased loads
  • Ageing equipment
  • An inability to meet current consents

For the long-term, Thames Water is also looking to invest in innovative, sustainable infrastructure, and wastewater treatment plant that ensures its customers benefit from a safe, dependable and resilient wastewater service, whilst also protecting and enhancing the environment.

Solution

2H designed, manufactured and supplied the components for a new trickling filter measuring 15.3m in diameter with media (shallow bed) 2.4m deep. Because it is built from BIOdek structured plastic media, the trickling filter meets Thames Water’s requirement for an energy-efficient, sustainable and resilient solution to meet the demands of a high-pressure environment with heavy effluent loads and stringent discharge consents.

2H also purpose-built the shallow-bed media support system using high-strength, long-life, concrete tiles which provide better drainage and are more effective resistance to corrosion than concrete blocks.

The solution included a customised Equiflo rotary distributor, which has tubular top discharge arms manufactured in 304 stainless steel, and is capable of handling 35 litres/sec. The distributor has a motor/gearbox speed controller and an automatic disengage to allow the unit to run on hydraulic reaction drive in case of motor failure.

Media used

443m3 BIOdek KFP619 structured PP (polypropylene) plastic media (150m2/m3).

Key outcomes

In the two years since going live, the purpose-built BIOdek trickling filter solution has continued to exceed expectations by:

  • Removing more than 75% of BOD
  • Achieving ammonia levels of c0.1% in the final effluent

The 2H Water Technologies trickling filter solution has delivered on all of Thames Water’s objectives by ensuring the Wheatley plant achieves its 100% compliance target with ammonia and BOD levels “not experienced for a long time” and “very safely below the required consent levels”. The solution also allows Thames Water to meet its commitment to safeguarding the local water environment.

Highlights

  • 100% consent compliance
  • Removal of 75% of BOD passing through the works
  • Better capacity for the downstream rock trickling filters, settlement tanks and sand filters
  • Provision of resilient, sustainable infrastructure for the future